GH Actions initial workflow

.github/workflows/build-test.yaml

@@ -0,0 +1,46 @@
+name: Arcade 3.0 Cross-Platform Tests
+
+on: [push, pull_request]
+
+jobs:
+  test:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        python-version: ['3.12']
+    runs-on: ${{ matrix.os }}
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v3
+      with:
+        python-version: ${{ matrix.python-version }}
+
+    - name: Install dependencies
+      run: |
+        uv python pin ${{ matrix.python-version }}
+        uv sync --no-dev
+    
+    - name: Set up virtual display (Linux only)
+      if: runner.os == 'Linux'
+      run: |
+        sudo apt-get install -y xvfb
+        export DISPLAY=:99
+        Xvfb :99 -screen 0 1024x768x24 > /dev/null 2>&1 &
+    
+    - name: Set up headless context (Windows only)
+      if: runner.os == 'Windows'
+      run: |
+        echo "import os" > setup_headless.py
+        echo "os.environ['PYGLET_HEADLESS'] = '1'" >> setup_headless.py
+        echo "import pyglet" >> setup_headless.py
+        echo "pyglet.options['shadow_window'] = False" >> setup_headless.py
+    
+    - name: Run tests
+      run: |
+        if [ "${{ runner.os }}" == "Windows" ]; then
+          python -c "import setup_headless"
+        fi
+        pytest tests/ --show-capture=no